The present invention relates to a valve provided in a gas flow path in which a gas containing, especially, at least one of corrosive gas and fine particle is allowed to flow, and a vacuum processing apparatus comprising the valve, and more specifically, to a valve having an excellent anti-corrosive property, and a high durability in function, and a vacuum processing apparatus comprising the valve.
In semiconductor factories, a great number of process gases are employed to process objects to be processed, such as semiconductor wafers. Further, gas pipes for feeding such process gases are provided with various types of valves for controlling the flow amounts of such gases. Note that each valve is used also as open/close means for opening/closing a connection path between chambers which constitute the vacuum processing apparatus.
The connection path connecting a processing chamber where a processing using a gas is carried out, to another chamber, and the gas flow path such as a gas pipe are exposed to gas in a great number of occasions. Therefore, especially when a gas having a corrosive property is used, there are various anti-corrosive measures are taken, such as that the section which constitutes the gas flow path is made of an anti-corrosive material.
FIG. 8 is a schematic diagram showing a part of a conventional vacuum processing apparatus which carries out a film formation process or etching process on an object to be processed, such as a semiconductor wafer. As shown in this figure, a vacuum processing apparatus A includes a processing chamber 1 for carrying out a predetermined processing on an object W to be processed with use of a gas under a predetermined vacuum atmosphere, a plurality of gas supplying pipes 2 and a gas exhaustion pipe 3, both connected to the processing chamber 1, and a valve 4 mounted on the gas exhaustion pipe 3. In the processing apparatus A described above, a plurality of kinds of process gases are supplied into the processing chamber 1 from these plurality of gas supplying pipes 2, and a predetermined process is carried out on the object W to be processed in the processing chamber 1. Further, unreacted gases, reaction byproducts and the like in the processing chamber 1 are exhausted from the processing chamber 1 via the gas exhaustion pipe 3. In this case, the flow of the exhaustion of the gas is controlled by the valve 4. Further, in many cases, a corrosive gas is used as the process gas, and therefore the gas flow paths for the processing chamber 1, the gas supplying pipe 2 and the gas exhaustion pipe 3 are treated completely to make it corrosion proof.
The valve 4 includes a valve main body, a valve member for opening/closing the gas flow path in the main body, a drive mechanism for driving the valve member and a sealing mechanism for isolating air-tightly the drive mechanism side from the valve drive mechanism. In this case, an anti-corrosive countermeasure is taken for the valve main body part which constitutes the gas flow path, but the sealing mechanism is not subjected to the anti-corrosive provisions. (Naturally, no anti-corrosive measures are taken for the drive mechanism.)
As described above, in the conventional valve, the anti-corrosive measures are not taken for the sealing mechanism, and therefore the seal mechanism is corroded with corrosive gases such as process gas and reaction byproducts. As a result, there is a danger of vacuum break caused from a corroded section of the sealing mechanism. Further, the reaction byproducts flowing through the gas exhaustion pipe 3 contains particles, and the seal mechanism may clog with some of the particles, thereby causing an operational error of the valve member or vacuum break.
An object of the present invention is to provide valve which can certainly prevent corrosion of a sealing mechanism for sealing a valve main body air-tightly with respect to a drive mechanism side, as well as the drive mechanism, and further can certainly prevent an operational error caused by particles contained in gas, thereby achieving a gas leakage proof and vacuum break proof, and a vacuum processing apparatus comprising such a valve.
The above-described object can be achieved by the following valve. That is, a valve comprising: a valve main body having an opening and forming a space which creates a part of a gas flow path; a first valve member, provided in the valve main body, for opening/closing the opening; and a drive mechanism, provided outside the valve main body, for moving the first valve member between a close position where the opening is closed and an open position where the opening is opened, wherein the drive mechanism has a rod to be reciprocated, an end of the rod extends into the valve main body through a through hole formed in the valve main body to be connected to the first valve member, the first valve member is moved between the close position and the open position as the rod is reciprocated, the valve further comprising: a sealing mechanism, which communicates into the valve main body via the through hole, for isolating the drive mechanism side air-tightly from the valve main body; and a second valve member, provided on the rod to move together with the rod as it is reciprocated, which closes the through hole when the first valve member is situated at the open or close position so as to isolate the sealing mechanism with respect to the valve main body.